C++ SmallString::pop_back方法代码示例

/// Determine whether the given text matches a property name.
static bool textMatchesPropertyName(StringRef text,
                                    const InheritedNameSet *allPropertyNames) {
  if (!allPropertyNames) return false;

  SmallString<16> localScratch;
  auto name = camel_case::toLowercaseWord(text, localScratch);

  // A property with exactly this name.
  if (allPropertyNames->contains(name)) return true;

  // From here on, we'll be working with scratch space.
  if (name.data() != localScratch.data())
    localScratch = name;

  if (localScratch.back() == 'y') {
    // If the last letter is a 'y', try 'ies'.
    localScratch.pop_back();
    localScratch += "ies";
    if (allPropertyNames->contains(localScratch)) return true;
  } else {
    // Otherwise, add an 's' and try again.
    localScratch += 's';
    if (allPropertyNames->contains(localScratch)) return true;

    // Alternatively, try to add 'es'.
    localScratch.pop_back();
    localScratch += "es";
    if (allPropertyNames->contains(localScratch)) return true;
  }

  return false;
}

/// Turn a sequence of our tokens back into a string that we can hand
/// to the MC asm parser.
static bool buildMSAsmString(Preprocessor &PP, SourceLocation AsmLoc,
                             ArrayRef<Token> AsmToks,
                             SmallVectorImpl<unsigned> &TokOffsets,
                             SmallString<512> &Asm) {
  assert(!AsmToks.empty() && "Didn't expect an empty AsmToks!");

  // Is this the start of a new assembly statement?
  bool isNewStatement = true;

  for (unsigned i = 0, e = AsmToks.size(); i < e; ++i) {
    const Token &Tok = AsmToks[i];

    // Start each new statement with a newline and a tab.
    if (!isNewStatement && (Tok.is(tok::kw_asm) || Tok.isAtStartOfLine())) {
      Asm += "\n\t";
      isNewStatement = true;
    }

    // Preserve the existence of leading whitespace except at the
    // start of a statement.
    if (!isNewStatement && Tok.hasLeadingSpace())
      Asm += ' ';

    // Remember the offset of this token.
    TokOffsets.push_back(Asm.size());

    // Don't actually write '__asm' into the assembly stream.
    if (Tok.is(tok::kw_asm)) {
      // Complain about __asm at the end of the stream.
      if (i + 1 == e) {
        PP.Diag(AsmLoc, diag::err_asm_empty);
        return true;
      }

      continue;
    }

    // Append the spelling of the token.
    SmallString<32> SpellingBuffer;
    bool SpellingInvalid = false;
    Asm += PP.getSpelling(Tok, SpellingBuffer, &SpellingInvalid);
    assert(!SpellingInvalid && "spelling was invalid after correct parse?");

    // We are no longer at the start of a statement.
    isNewStatement = false;
  }

  // Ensure that the buffer is null-terminated.
  Asm.push_back('\0');
  Asm.pop_back();

  assert(TokOffsets.size() == AsmToks.size());
  return false;
}

/// \brief Find the end of the word starting at the given offset
/// within a string.
///
/// \returns the index pointing one character past the end of the
/// word.
static unsigned findEndOfWord(unsigned Start, StringRef Str,
                              unsigned Length, unsigned Column,
                              unsigned Columns) {
  assert(Start < Str.size() && "Invalid start position!");
  unsigned End = Start + 1;

  // If we are already at the end of the string, take that as the word.
  if (End == Str.size())
    return End;

  // Determine if the start of the string is actually opening
  // punctuation, e.g., a quote or parentheses.
  char EndPunct = findMatchingPunctuation(Str[Start]);
  if (!EndPunct) {
    // This is a normal word. Just find the first space character.
    while (End < Length && !isspace(Str[End]))
      ++End;
    return End;
  }

  // We have the start of a balanced punctuation sequence (quotes,
  // parentheses, etc.). Determine the full sequence is.
  SmallString<16> PunctuationEndStack;
  PunctuationEndStack.push_back(EndPunct);
  while (End < Length && !PunctuationEndStack.empty()) {
    if (Str[End] == PunctuationEndStack.back())
      PunctuationEndStack.pop_back();
    else if (char SubEndPunct = findMatchingPunctuation(Str[End]))
      PunctuationEndStack.push_back(SubEndPunct);

    ++End;
  }

  // Find the first space character after the punctuation ended.
  while (End < Length && !isspace(Str[End]))
    ++End;

  unsigned PunctWordLength = End - Start;
  if (// If the word fits on this line
      Column + PunctWordLength <= Columns ||
      // ... or the word is "short enough" to take up the next line
      // without too much ugly white space
      PunctWordLength < Columns/3)
    return End; // Take the whole thing as a single "word".

  // The whole quoted/parenthesized string is too long to print as a
  // single "word". Instead, find the "word" that starts just after
  // the punctuation and use that end-point instead. This will recurse
  // until it finds something small enough to consider a word.
  return findEndOfWord(Start + 1, Str, Length, Column + 1, Columns);
}

//.........这里部分代码省略.........
        break;
      }

      case PartOfSpeech::Preposition:
      case PartOfSpeech::Gerund:
      case PartOfSpeech::Unknown:
        return name;
      }
      break;

    case NameRole::BaseName:
    case NameRole::FirstParameter:
    case NameRole::Partial:
    case NameRole::SubsequentParameter:
      // Classify the part of speech of the word before the type
      // information we would strip off.
      switch (getPartOfSpeech(*nameWordRevIter)) {
      case PartOfSpeech::Preposition:
        if (role == NameRole::BaseName) {
          // Strip off the part of the name that is redundant with
          // type information, so long as there's something preceding the
          // preposition.
          if (std::next(nameWordRevIter) != nameWordRevIterEnd)
            name = name.substr(0, nameWordRevIter.base().getPosition());
          break;
        }

        SWIFT_FALLTHROUGH;

      case PartOfSpeech::Verb:
      case PartOfSpeech::Gerund:
        // Don't prune redundant type information from the base name if
        // there is a corresponding property (either singular or plural).
        if (allPropertyNames && role == NameRole::BaseName) {
          SmallString<16> localScratch;
          auto removedText = name.substr(nameWordRevIter.base().getPosition());
          auto removedName = camel_case::toLowercaseWord(removedText,
                                                         localScratch);

          // A property with exactly this name.
          if (allPropertyNames->contains(removedName)) return name;

          // From here on, we'll be working with scratch space.
          if (removedName.data() != localScratch.data())
            localScratch = removedName;

          if (localScratch.back() == 'y') {
            // If the last letter is a 'y', try 'ies'.
            localScratch.pop_back();
            localScratch += "ies";
            if (allPropertyNames->contains(localScratch)) return name;
          } else {
            // Otherwise, add an 's' and try again.
            localScratch += 's';
            if (allPropertyNames->contains(localScratch)) return name;

            // Alternatively, try to add 'es'.
            localScratch.pop_back();
            localScratch += "es";
            if (allPropertyNames->contains(localScratch)) return name;
          }
        }

        // Strip off the part of the name that is redundant with
        // type information.
        name = name.substr(0, nameWordRevIter.base().getPosition());
        break;

      case PartOfSpeech::Unknown:
        // Assume it's a noun or adjective; don't strip anything.
        break;
      }
      break;
    }

  }

  // If we ended up with a vacuous name like "get" or "set", do nothing.
  if (isVacuousName(name))
    return origName;

  switch (role) {
  case NameRole::BaseName:
  case NameRole::BaseNameSelf:
  case NameRole::Property:
    // If we ended up with a keyword for a property name or base name,
    // do nothing.
    if (isKeyword(name))
      return origName;
    break;

  case NameRole::SubsequentParameter:
  case NameRole::FirstParameter:
  case NameRole::Partial:
    break;
  }

  // We're done.
  return name;
}

/// StringifyArgument - Implement C99 6.10.3.2p2, converting a sequence of
/// tokens into the literal string token that should be produced by the C #
/// preprocessor operator.  If Charify is true, then it should be turned into
/// a character literal for the Microsoft charize (#@) extension.
///
Token MacroArgs::StringifyArgument(const Token *ArgToks,
                                   Preprocessor &PP, bool Charify,
                                   SourceLocation ExpansionLocStart,
                                   SourceLocation ExpansionLocEnd) {
  Token Tok;
  Tok.startToken();
  Tok.setKind(Charify ? tok::char_constant : tok::string_literal);

  const Token *ArgTokStart = ArgToks;

  // Stringify all the tokens.
  SmallString<128> Result;
  Result += "\"";

  bool isFirst = true;
  for (; ArgToks->isNot(tok::eof); ++ArgToks) {
    const Token &Tok = *ArgToks;
    if (!isFirst && (Tok.hasLeadingSpace() || Tok.isAtStartOfLine()))
      Result += ' ';
    isFirst = false;

    // If this is a string or character constant, escape the token as specified
    // by 6.10.3.2p2.
    if (tok::isStringLiteral(Tok.getKind()) || // "foo", u8R"x(foo)x"_bar, etc.
        Tok.is(tok::char_constant) ||          // 'x'
        Tok.is(tok::wide_char_constant) ||     // L'x'.
        Tok.is(tok::utf8_char_constant) ||     // u8'x'.
        Tok.is(tok::utf16_char_constant) ||    // u'x'.
        Tok.is(tok::utf32_char_constant)) {    // U'x'.
      bool Invalid = false;
      std::string TokStr = PP.getSpelling(Tok, &Invalid);
      if (!Invalid) {
        std::string Str = Lexer::Stringify(TokStr);
        Result.append(Str.begin(), Str.end());
      }
    } else if (Tok.is(tok::code_completion)) {
      PP.CodeCompleteNaturalLanguage();
    } else {
      // Otherwise, just append the token.  Do some gymnastics to get the token
      // in place and avoid copies where possible.
      unsigned CurStrLen = Result.size();
      Result.resize(CurStrLen+Tok.getLength());
      const char *BufPtr = Result.data() + CurStrLen;
      bool Invalid = false;
      unsigned ActualTokLen = PP.getSpelling(Tok, BufPtr, &Invalid);

      if (!Invalid) {
        // If getSpelling returned a pointer to an already uniqued version of
        // the string instead of filling in BufPtr, memcpy it onto our string.
        if (ActualTokLen && BufPtr != &Result[CurStrLen])
          memcpy(&Result[CurStrLen], BufPtr, ActualTokLen);

        // If the token was dirty, the spelling may be shorter than the token.
        if (ActualTokLen != Tok.getLength())
          Result.resize(CurStrLen+ActualTokLen);
      }
    }
  }

  // If the last character of the string is a \, and if it isn't escaped, this
  // is an invalid string literal, diagnose it as specified in C99.
  if (Result.back() == '\\') {
    // Count the number of consecutive \ characters.  If even, then they are
    // just escaped backslashes, otherwise it's an error.
    unsigned FirstNonSlash = Result.size()-2;
    // Guaranteed to find the starting " if nothing else.
    while (Result[FirstNonSlash] == '\\')
      --FirstNonSlash;
    if ((Result.size()-1-FirstNonSlash) & 1) {
      // Diagnose errors for things like: #define F(X) #X   /   F(\)
      PP.Diag(ArgToks[-1], diag::pp_invalid_string_literal);
      Result.pop_back();  // remove one of the \'s.
    }
  }
  Result += '"';

  // If this is the charify operation and the result is not a legal character
  // constant, diagnose it.
  if (Charify) {
    // First step, turn double quotes into single quotes:
    Result[0] = '\'';
    Result[Result.size()-1] = '\'';

    // Check for bogus character.
    bool isBad = false;
    if (Result.size() == 3)
      isBad = Result[1] == '\'';   // ''' is not legal. '\' already fixed above.
    else
      isBad = (Result.size() != 4 || Result[1] != '\\');  // Not '\x'

    if (isBad) {
      PP.Diag(ArgTokStart[0], diag::err_invalid_character_to_charify);
      Result = "' '";  // Use something arbitrary, but legal.
    }
  }
//.........这里部分代码省略.........